linux-kernel - [PATCH AUTOSEL 4.19 16/20] ALSA: hda/hdmi: fix race in monitor detection during probe

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Message-Id: <20200507142917.26612-16-sashal@kernel.org>
Date:   Thu,  7 May 2020 10:29:12 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Kai Vehmanen <kai.vehmanen@...ux.intel.com>,
        Takashi Iwai <tiwai@...e.de>, Sasha Levin <sashal@...nel.org>,
        alsa-devel@...a-project.org
Subject: [PATCH AUTOSEL 4.19 16/20] ALSA: hda/hdmi: fix race in monitor detection during probe

From: Kai Vehmanen <kai.vehmanen@...ux.intel.com>

[ Upstream commit ca76282b6faffc83601c25bd2a95f635c03503ef ]

A race exists between build_pcms() and build_controls() phases of codec
setup. Build_pcms() sets up notifier for jack events. If a monitor event
is received before build_controls() is run, the initial jack state is
lost and never reported via mixer controls.

The problem can be hit at least with SOF as the controller driver. SOF
calls snd_hda_codec_build_controls() in its workqueue-based probe and
this can be delayed enough to hit the race condition.

Fix the issue by invalidating the per-pin ELD information when
build_controls() is called. The existing call to hdmi_present_sense()
will update the ELD contents. This ensures initial monitor state is
correctly reflected via mixer controls.

BugLink: https://github.com/thesofproject/linux/issues/1687
Signed-off-by: Kai Vehmanen <kai.vehmanen@...ux.intel.com>
Link: https://lore.kernel.org/r/20200428123836.24512-1-kai.vehmanen@linux.intel.com
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 sound/pci/hda/patch_hdmi.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
index c67fadd5aae53..b77cded6457a8 100644
--- a/sound/pci/hda/patch_hdmi.c
+++ b/sound/pci/hda/patch_hdmi.c
@@ -2209,7 +2209,9 @@ static int generic_hdmi_build_controls(struct hda_codec *codec)

 	for (pin_idx = 0; pin_idx < spec->num_pins; pin_idx++) {
 		struct hdmi_spec_per_pin *per_pin = get_pin(spec, pin_idx);
+		struct hdmi_eld *pin_eld = &per_pin->sink_eld;

+		pin_eld->eld_valid = false;
 		hdmi_present_sense(per_pin, 0);
 	}

-- 
2.20.1